Fly High Pro X Series Fat Sac Ballast Bag 2011 - The Fly High Pro X Series Fat Sac Ballast Bag is the original fat sac redefined and setting new industry standards. Made from super durable whitewater rafting material called Valmex, place the Fly High Pro X Series Fat Sac Ballast Bag on either side of the engine and add 1500 lbs. of ballast when full. Don’t stress about the perfect fit either as these bags will conform to fit anywhere you want.